Curling up under the blankets with an e-book before bedtime could damage the sleep and affect the health, new study shows.
A team of scientists from Harvard Medical School studied the difference between reading normal, paper books and reading using e-readers that emit light, before going to sleep.

The researchers found that after reading from an e-reader, it took longer to fall asleep, which leads to a poorer sleep quality and the subjects were more tired in the morning. Experts said that original Kindle readers that do not emit light are not a threat to the sleep quality or to the overall health.

The researchers advised against reading from devices that emit light because it can affect their sleep and their overall health. People should minimize the exposure to light-emitting devices before sleeping hours because the human body is kept in tune with the rhythm of day and night using its own internal clock. This internal body clock uses light to tell what time it is.

Blue light coming from devices like smartphones, tablets and other LED lighting can disrupt the body clock, researchers say. Blue light coming from these devices can slow down or even prevent the production of melatonin, which is the sleep hormone.

For the study that proved e-readers are not healthy, the scientists locked 12 volunteers in a sleep laboratory and kept them there for 12 weeks. The subjects spent five days reading from an iPad and five days reading from a regular book. The researchers took blood samples regularly and noticed that the production of melatonin was reduced considerably after reading an e-book.

Also, those reading from the iPads had problems falling asleep, experienced less deep sleep hours and were more tired in the morning. He researchers said that other reading devices that emit light, like Kindle Fire and Nook would have the same impact on our health.

The scientists advised that people should minimize their use of light-emitting e-readers in the evening, especially teenagers who spend a lot of time on their smartphones and tablets until late into the night and have troubles waking up in the morning to go to school.
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